1. Field of the Invention
The present invention relates to a time code processing apparatus, a time code processing method, a program, and a video signal playback apparatus. In particular, the present invention relates to a technique of, when playing back a first video signal in 24 frame/s progressive format as a second video signal in 30 frame/s interlaced format, generating second time code values for the second video signal based on first time code values that are provided in the first video signal at intervals of a given number of frames.
2. Description of the Related Art
Movie films and so on are commonly shot at 24 frames per second. In order to allow video taken with a video camera, instead of a film camera, to be displayed in a manner similar to that in which video recorded on a film is displayed, a video signal in 24 frame/s progressive format (hereinafter referred to as a “24p video signal”) is commonly generated. Meanwhile, in television devices, video is commonly displayed using a video signal in 30 frame/s interlaced format (hereinafter referred to as a “60i video signal”). As such, 2:3 pulldown, 2:3:3:2 pulldown, and so on are commonly performed to convert the 24p video signal to the 60i video signal.
Referring to FIG. 9, in the 2:3 pulldown, two fields of 60i video signal are generated from a first frame of the 24p video signal. Three fields of 60i video signal are generated from a second frame of the 24p video signal. Two fields of 60i video signal are generated from a third frame of the 24p video signal. Three fields of 60i video signal are generated from a fourth frame of the 24p video signal. In this manner, five frames of 60i video signal are generated from four frames of 24p video signal. This process corresponds to one sequence. This sequence is repeated to convert the 24p video signal to the 60i video signal. Note that, in FIG. 9 and FIG. 10 described below, “t” and “b” in the 60i video signal represent a top field and a bottom field, respectively.
Referring to FIG. 10, in the 2:3:3:2 pulldown, two fields of 60i video signal are generated from the first frame of the 24p video signal. Three fields of 60i video signal are generated from the second frame of the 24p video signal. Three fields of 60i video signal are generated from the third frame of the 24p video signal. Two fields of 60i video signal are generated from the fourth frame of the 24p video signal. This process corresponds to one sequence. This sequence is repeated to convert the 24p video signal to the 60i video signal. In the case where the 2:3:3:2 pulldown is applied, conversion of the 60i video signal to the 24p video signal is easily accomplished by, in each sequence, eliminating the third frame of the 60i video signal and recovering each two-field signal to a one-frame signal.
Further, in order to facilitate edition and the like, time code values are provided so as to be associated with the video signals. When converting the 24p video signal to the 60i video signal, it is necessary to generate time code values for the 60i video signal based on time code values for the 24p video signal. As such, Japanese Patent Laid-Open No. 2003-289512 and U.S. Pat. No. 7,212,733 corresponding thereto, for example, disclose a technique of converting the time code values for the 24p video signal to the time code values for the 60i video signal at the time of normal playback or varied-speed playback.